1. Technical Field
The present invention relates to a projector.
2. Related Art
Projectors using discharge lamps such as high-pressure mercury lamps and metal halide lamps have been put into practical use. Some of the projectors having an operation mode (standby mode) of darkening projected images while maintaining the lighting states of the discharge lamps when no image signal is input or when a specific operation is performed by a user have been developed. As the projector, for example, JP-A-2007-025054 discloses a projector including means for controlling power supplied to a discharge lamp to the minimum value when no image signal is input or the like in order to suppress power consumption.
However, if the power supplied to the discharge lamp is continuously set lower for driving while the lighting state of the discharge lamp is maintained, the electrode temperature of the discharge lamp becomes lower and a blackening phenomenon that the electrode material (tungsten or the like) precipitates on the envelope of the discharge lamp becomes easier to occur. When the blackening phenomenon occurs, the blackened part absorbs light and the temperature of the discharge lamp rises, the glass used for the envelope or the like is crystallized, and devitrification phenomenon is caused. When the devitrification phenomenon occurs, the illuminance of the discharge lamp becomes lower and the envelope becomes easier to break. Therefore, it is important not to cause the blackening phenomenon for the longer life of the discharge lamp.